Sound-reproducing device



uw.l 8,1925. 1,564,968

. N. A. KURMAN' souNn REPRODUCING DEVICE 2 sheets-smit 1 Filed Dec. 192.2

Dec. 8,192s'. f 1,564,968

l N. A. KURMAN 7 v l SOUND REPRODUGING DEvICEj Filed Deo. 2, 1922 zsheefsj-shnf 2 Patented Dec. 8, 1925.

UNITED STATES NATHAN A..KURMAN, F NEW YORK, N. Y.

- SOUND-REPRODUCING DEVICE.

Appmammmea 'December 2, 1922.` serial No. 604532.

To all 'whom t may concern.'

Be it known-that I, NATHAN A. KURMAN,

a citizen of the United States, residing at the city of New York, borough of Manhattan,

" in the county and State of Newl York, have invented certain new and useful Improvements in Sound-Re reducing Devices, of

which. the following 1s a full, clear, and exact specification.

This invention relates to improvements 1n sound receiving.- and transmitting instru-l ments, such as telephone recelvers and trans-- mitte'rs, .microphone repeaters, and more particularly to those instruments which are,

adapted for use inV loud-speaking systems or any loud transmission systems, and the same hasvfor its object moreparticularly to pro'- vide an apparatus ofthe character specified which shall b'e comparatively simple in construction, eiicient in operation, and easily rregulated or adjusted to meet the varying conditions of service.

- Further, said, invention has for its object to provide counterbalancing means effective to counterbalance not only the tensionvdue to the influence or attraction of the permanent magnet butalso the tension due to the initially impressed voltages on the electromagnetic circuit, such as the voltage impressed upon the coil of the receiver which is operatively-associated with the plate circuit of an audion tube.

fFurther, said invention has for its object to provideV an instrument in which the magnetic influence upon the armature and associated parts may be accurately counterbalanced in order to render the diaphragm more sensitive so that sounds of greater volume Y'and purer tone may be produced.

Further, said invention has for its object to provide an instrument in which the mag'- netlc influence upon the armature and associated parts may be adjusted without placin the diaphragm under tension or unduly aicting the resiliency thereof.

Further, said invention has for its object to provide. an instrument embodying a'leverage whereby the vibrations of the armature of the permanent magnet may be taken up by` a member heavy enough to convey all vibrations to a light member connected to the diaphragm, vso that the latter may operate with greater etliciency. v v

Further, said -'nvention has for its object to provide an instrument embodying a leverjusting means;

age between the armature f and the'diaphragm wherein the tension of thej armature of thev permanent magnet thereon places no bending `stress u on the leverage member connected to said diaphragm so as not to affect tl1e,resiliency of said member. The full resiliency. of vsaid member is therefore available to transmit vibrations to the diaphragm.

' Other objects and advantages will in part be obvious and in part be specifically. pointed out in the specification.

To the attainment of the aforesaid objects i and ends my-invention consists in the novel' details of construction, and in the combina? tion, connection and arrangement of parts hereinafter more fully described and then pointed out in the c1a1ms.

. In the accompanying drawings- Figure 1 is a sectional view showing one form of telephone receiver embodying my invention; l

AFig. 2 is an enlarged detailsectional view on the line 2-2 o1V Fig. 1, showing the ad- Fig. 3 is a detail perspective view of th adjusting vmeans and support;

Fig.4 is a view similar to Fig. 1, showing a modified structure, and

' Fig. 5 is an enlarged detail face view of the-adjusting means shown in Fig. 4.

Referring to Fig. 1, there is shown a permanent magnet 10 having one. leg provided with an extension'llnd the other leg provided with a pole-piece 1.2 surrounded by a coil 13. Thel extension 11 has an armature 14 pivotally mounted thereon as by a notch and groove connection. Fixed to the magnet 10 is a frame 16 having at its upper end a plate 18 supporting a'washer 19 and an apertured front plate 20. A diaphragm- 22 isclamped between washers 19 by the plate 20. Within the aperture in plate 20 is secured a short tube which'is adapted for connection tol some type of resonator.

Upon a'knife-edge .30- formed on a mem' ber fixed to frame 16 is pivoted a lever 31 having a bifurcated arm to one sideo'f the pivot, and a single arm 32 in the form'of a spring to the other lside .of the pivot. "The bifurcated arm consists of a lightmember 33 connected by an eye-bolt 35 'to the diaphragm' 22, and a heavy member 34 connected byalink `36 to a-pin 37 on the end of armature' 14 opposite the pole-piece l12. An`

adjusting screw 40 passes through plate 18 and engages the outer end ofk the spring 32.

In operation, the adjusting screw is operated to raise the bifurcated arm until armature 14 is held a proper distance above the pole-piece 12, thus neutralizing the attraction of the magnet. During thisoperation v the diaphragm) due to some initially im- 6- claims.

pressed voltage such as isl sent through the coil 13 in radiotelephone systems. Since the link 36 is not connected to arm 33 there 1s at no time any bending stress 1n the arm connected to the diaphragm, so that the resilience of said arm is not` diminished. The arm 33 can therefore be made light and resilient and so add to the sensitivity and efficiency of the diaphragm, while the arm 34 can be constructed heavy enough to transmit the vibrations from the armature to the diaphragm. A n A A modi'ed structure is illustrated in Flgs.

4 and 5. All of the parts in these figures arev the same as in Fig. 1 with the exception of the mounting for the lever and the spring adjustment. In this instance the lever comprises only the bifurcated arm consisting of the light upper member 33 connected to the diaphragm and the heavy member 34 connected to the armature. The bifurcated arm extends outside of frame 16 and is pivoted on knife edges 50 upon the outside of said frame forming a horizontal pivotal axis. To rock said lever about said axis to vary the pull upon the armature, for the purposes hereinbefore described, there are yprovided leaf springs 51 and 52 both fixedv at one end to said lever. The spring 51 extends upwardly-while theI spring 52 extends downwardly. Cooperating with the free ends of said springs are adjusting screws 53, 54 extending into a bracket 55. The enclosing casing or base may be provided with apertures 56 forthe `introduction of a screwdriver or other instrument to actuate said screws 52, y53. It will bev obviousthat by varying the tension upon said springs any desired position of the lever may be obtained.

The above description, illustrates the prin- -ciples embodied in my invention but it will be understoodthat various changes and modifications may be made within the scope of the invention as defined in the annexed 'Having thus described my said invention what I claim and desire to secure by Letters v Patent is:

1. An apparatus of the character described, comprising a sound-responsive member, a diaphragm, and means acting on said member to counterbalance the magnetic forces acting thereon; said diaphragm when inactive being unstressed, Substantially as specified.

2. An apparatus of the character described, 4 comprising a member, a diaphragm, a connecting member between said sound-responsive member and said diaphragm, and means included in said connecting member to counterbalance the 'I magnetic forces acting on said sound-responslve member Without placing said dlaito counteract the ,magneticfforces acting on saielesound-responsive member While maintaining the dia'hragm in said normal con-v dition,substant1ally as specified.

5. An apparatus of the character de? scribed, comprising a sound-responsive member, a diaphragm, means connecting said diaphragm and sound-responsive member, means for exerting a permanent magnetic influence on vsaid sound-responsive member, and means for balancing said member against said permanent magnetic infiuence without appreciably stressin 1 said diaphragm substantially as speci ed.

6. An apparatus of the character described, comprising a sound-responsive member, a diaphragm, means connecting said diaphragm and said sound-responsive member, means for exerting a permanent magnetic influence and means for impressing a constant electromagnetic influence on said sound-responsive member, and means for balancing said sound-responsive member againstI said magnetic /and electromagnetic iniuence without materially stressing said diaphragm substantially as specified.

7. An apparatus of the character described, comprising a sound-responsive member, a diaphragm, a ,movable member,

sound-responsive phragm, when inactive under appreciable arms extending therefrom, a flexible connection tween one of said arms and said 'sound-responsive member, and a flexible connection between the other of said arms and said diaphragm, substantially as specified. 1

8. An apparatus of the character dev scribed comprising a sound-responsive member,l a diaphragm, a movable member, arms extending therefrom; one of said arms being 1i hter than the other and connected to sai diaphragm, and means adapted to exertv a stress transversely of the Vother of said arms connectingthe same to said soundrfsponsive member, lsubstantially las speci- 9. An apparatus of the character described comprising a sound-responsive Imember, a diaphragm, a movable member, arms extending therefrom, a connection between one of sai'd, arins and said diaphragm, and a connection between the other of said arms and said sound-responsive member, and means'for adjustin said movable member to connterbalance sai sound-responsive member, substantially as specified. l

10. An apparatus. of the character de' diaphragm comprising a lever having one of its arms bifurcated, one of said bifurcations being flexibly connected to said, diaphragm and the other of said bifurcations being flexibly connected to said armature, sub-l stantially as specified.

1-2. An apparatus of the character described, comprising an electromagnet, an armature therefor, a diaphragm, a connects" ing member between said armature and said dia hragm com risin a lever havin one ofv iJts arms bifrcate, one of said ifurcations being connected to saiddiaphragm and the other of said bifurcations being connected to said armature, and means for applying a tension to said last-namedbifurcation without placing said @first-named bifurcation under stress, substantially as specified. y

13. An apparatus of the vcharacter described, comprising an electromagnet, an

armature therefor, a dia hragm, a connectingv member between sai armature and said diaphragm comprising a lever hav' one of 1ts arms bifurcated, one of said bi cations 4being connected to said diaphragm, the other of vsaid bifurcations being connected to said armature, resilient means for applying a tension to said last-named bifurcation to counterbalance ysaid armature means to permit of the disconnection of said diaphragm from said first-named bifurcation, and means for varying said tension at will, substantially as specified.l a

Signed at the city of New York, in the county and State of New York, this sixth day of October, one thousand nine hundred and twenty-two. y

f NATHAN A. KURMAN. 

